Generally, in a video cassette recorder, the tension of a tape running between a take-up reel and a supply reel must be constantly controlled or adjusted to a desired level depending on the operating mode of the video cassette recorder. For this reason, various types of tape tension adjusting devices have been proposed and employed to adjust the tension of the running magnetic tape.
One of the prior art tape tension adjusting devices is illustrated in FIG. 1. In the illustrated device, after a magnetic tape T is arranged onto a predetermined travel path between a supply reel 11 and a take-up reel (not shown), a tension lever 1 pivotally mounted on a deck 10 through a hinge 3 is permitted to be biased toward the magnetic tape T by a spring 4. The tension lever 1 has at its distal end a tension pole 2 for pressing the running magnetic tape T. The tension pole 2 presses the magnetic tape T in response to the rotation of the tension lever 1, as represented with an arrow, thereby forcing a band brake 5, whose one end is connected to the tension lever 1 through a first band holder 6, into an operative position. At the operative position, the band brake 5 exerts a braking force on the supply reel 11 in response to a further rotation of the tension lever 1. The band brake 5 is supported at the other end thereof by a second band holder 7 mounted on the deck.
On the other hand, one end of the above-mentioned spring is fixed at a protuberance 8 provided on a proximal end of the tension lever 1 and the other end thereof is fixed at a hook 9 mounted on the deck 10. The hook 9 is provided with three anchor portions 9a, 9b, 9c, each of which has a different distance from the protuberance 8. This arrangement allows the tape tension adjusting range of the tension lever 1 to be changed by having the one end of the spring 4, which is fixed to one of the anchor portions 9a, 9b, 9c of the hook 9, fixed to any other anchor portion.
However, in such a tension adjusting device, the tape tension of the tension lever is changed incrementally due to the set distance between the anchor portions of the hook, which, in turn, prevents the tape tension to be adjusted with a greater precision.